U.S. patent application number 13/117185 was filed with the patent office on 2012-05-10 for method for purifying lipid material.
This patent application is currently assigned to NESTE OIL OYJ. Invention is credited to Mervi Hujanen, Annika Malm, Reijo Tanner.
Application Number | 20120116103 13/117185 |
Document ID | / |
Family ID | 43640686 |
Filed Date | 2012-05-10 |
United States Patent
Application |
20120116103 |
Kind Code |
A1 |
Hujanen; Mervi ; et
al. |
May 10, 2012 |
Method for Purifying Lipid Material
Abstract
The present invention relates to a method for purification of
lipid material originating from biological material. In the method
the lipid material comprising acylglycerols and phosphorus
impurities and at least one added nonpolar solvent and at least one
added polar solvent is provided into a reaction zone whereby at
least a two phase system comprising a nonpolar phase and a polar
phase is formed. The phase system is heated in the closed reaction
zone under mixing at a temperature from 150.degree. C. to
300.degree. C. and at a pressure wherein said solvents are in
subcritical state, preferably of below 100 bar, dependent on the
vapor pressure of the selected solvents, until the phosphorus
impurity is removed from the polar phase. Sub-sequently, the
nonpolar phase including the purified oil comprising acylglycerols
is separated and recovered from said phase system.
Inventors: |
Hujanen; Mervi; (Helsinki,
FI) ; Malm; Annika; (Helsinki, FI) ; Tanner;
Reijo; (Hikia, FI) |
Assignee: |
NESTE OIL OYJ
Espoo
FI
|
Family ID: |
43640686 |
Appl. No.: |
13/117185 |
Filed: |
May 27, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61411145 |
Nov 8, 2010 |
|
|
|
Current U.S.
Class: |
554/9 ; 554/175;
554/207; 554/210; 554/8 |
Current CPC
Class: |
C11B 3/006 20130101;
Y02E 50/10 20130101; C10L 1/1802 20130101; C11B 1/10 20130101; C10L
1/026 20130101; C10L 1/18 20130101 |
Class at
Publication: |
554/9 ; 554/8;
554/175; 554/210; 554/207 |
International
Class: |
C11B 1/00 20060101
C11B001/00; C11B 7/00 20060101 C11B007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 8, 2010 |
EP |
10190309.4 |
Claims
1. A method for purification of lipid material originating from
biological material characterized in that said method comprises the
steps of a. providing said lipid material comprising acylglycerols
and phosphorus impurities and at least one added nonpolar solvent
and at least one added polar solvent into a reaction zone whereby
at least a two phase system comprising a nonpolar phase and a polar
phase is formed, and b. heating said phase system in the closed
reaction zone under mixing at a temperature from 150.degree. C. to
300.degree. C. and at a pressure wherein said solvents are in
subcritical state, preferably of below 100 bar, dependent on the
vapor pressure of the selected solvents, until the phosphorus
impurity is removed from the polar phase, and c. separating and
recovering from said phase system said nonpolar phase including the
purified oil comprising acylglycerols.
2. The method according to claim 1 characterized in that said
phosphorus impurities are in the form of phospholipids.
3. The method according to claim 1 characterized in that said
biological material comprises plant, animal or microorganism
material.
4. The method according to claim 3 characterized in that said plant
material is selected from the group of vegetable fat plants,
preferably selected from the group of seed oil, vegetable oil,
fruit oil and pine oil, more preferably selected from rape-seed,
canola, soybean, palm, cotton, sunflower, camelina, jatropha, corn,
hemp and used cooking oil.
5. The method according to claim 2 characterized in that said
animal material comprises animal fat, preferably rendered animal
fat, more preferably selected from beef, pork, sheep or poltry
lard, tallow, butter or fat or mixtures thereof.
6. The method according to claim 2 characterized in that said
microorganism material is selected from the group of algae,
bacteria, fungi, preferably algae and fungi, most preferably
algae.
7. The method according to claim 1 characterized in that said lipid
material is oil containing residue or waste originating from oil
extraction processes, preferably from degumming.
8. The method according to claim 1 characterized in that said lipid
material further comprises complex lipids selected from glycolipids
and sphingolipids.
9. The method according to claim 1 characterized in that said
temperature is from 160.degree. C. to 260.degree. C., preferably
from 180.degree. C. to 250.degree. C., more preferably from
190.degree. C. to 240.degree. C., such as from 200.degree. C. to
230.degree. C., or even from 210.degree. C. to 230.degree. C.
10. The method according to claim 1 characterized in that said at
least two phase system further comprises a third phase, preferably
said at least two phase system further comprises a third phase
comprising solid impurities or solid phase residue formed during
processing.
11. The method according to claim 1 characterized in that said
nonpolar solvent comprises aliphatic or cyclic alkanes of
C.sub.3-C.sub.20 or mixtures thereof, preferably C.sub.5-C.sub.16
alkanes or mixtures thereof, more preferably product from
hydrodeoxygenation process, LIAV, hexane, heptanes, octane or
mixtures thereof.
12. The method according to claim 1 characterized in that said
polar solvent comprises water, preferably a mixture of water and an
alcohol readily soluble in water, more preferably a mixture of
water and an alcohol selected from methanol, ethanol and a mixture
thereof.
13. The method according to claim 1 characterized in that said
purified oil is recovered dissolved in the nonpolar solvent and the
impurities are removed from the nonpolar phase together with the
polar phase or as a solid.
14. The method according to claim 1 characterized in that the ratio
of said lipid material to said nonpolar solvent is less than 10:1,
preferably 1:1, more preferably 1:5, most preferably 1:10.
15. The method according to claim 1 characterized in that the ratio
of the combiped amount of said lipid material and nonpolar solvent
to polar solvent is more than 1:10, preferably 1:5, more preferably
1:1, most preferably at least 5:4, such as 10:1.
16. Use of said purified oil obtained from the method according to
claim 1 for production of biodiesel, renewable diesel, jet fuel,
gasoline or base oil components.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a method for purification
of lipid material of biological origin. Especially, purified oil
suitable for use as feedstock in the production of a renewable fuel
component is obtained by the present method.
BACKGROUND OF THE INVENTION
[0002] Today liquid fuel components are mainly based on crude oil.
There is an ever growing demand for liquid fuels with lower
CO.sub.2 emissions compared to crude oil based fuels. Various
renewable sources have been used as alternatives for crude oil
fuels.
[0003] Vegetable oils and animal based fats can be processed for
use as liquid biofuels in the form of fatty acid esters or
hydrocarbons. Lipids for use in biofuels can also be produced in
microorganisms such as algae, fungi and bacteria.
[0004] A typical problem with the use of animal based fats or
vegetable oils, in particular microbial oils for liquid fuel
production, is that they tend to contain significant amounts of
metal and phosphorus impurities. These undesirable impurities are
difficult to remove from renewable source material without
simultaneously removing some of the valuable components. The
impurities cause problems, for example, in the fuel production in
form of catalyst poisons and/or corrosive materials. Deposits of
metal and phosphorus compounds are likely to result in catalyst
deactivation and plugging of the reactor catalyst bed in refining
processes. In addition to phosphorus and metals animal fats
frequently further contain thousands of ppms nitrogen which is hard
to remove by existing pretreatment procedures.
[0005] Therefore, it is often required to use pretreatment steps or
precleaning for removal of these undesired components from the oil
product. Common treatment methods such as water degumming, soft
degumming, acid degumming, wet bleaching and dry bleaching, for
example, are able to remove most of the phospholipids and their
salts from the feed stream. A disadvantage in using these methods
is that a notable amount of feed which could be reformed into fuel
is lost. In a degumming process especially phospholipids as well as
metal impurities are removed in the form of gums. The formed gums
contain significant amount of lipid material in the form of complex
lipids thus decreasing the yield in fuel production. Other
compounds used in oil purification like bleaching earth may become
annoying waste that is difficult and expensive to handle, and
simultaneously valuable agricultural fertilizer components are
lost.
[0006] Microorganisms such as algae, archaea, bacteria and fungi
including filamentous fungi and yeast may contain triglycerides up
to 80% of their total dry matter content. However, oil from
microbial biomass which is suitable as precursor for fuel
production is scarce on the market. This is mainly due to lack of
efficient and economical methods for providing good quality oil
from microbial biomass. The typical drawbacks are high impurity
contents and/or low yield.
[0007] When microbial biomass is used as feedstock the high amount
of phospholipids i.e. membrane lipids from the total lipid content
complicates the treatment even more. These lipids are typically in
the form of metal salts additionally providing high metal content
into oil. Traditionally, these phospholipids as such have been
removed before further processing whereby usable lipid content is
lost. The extraction of oil at a high temperature produces oil with
less impurities. However, many valuable ingredients contained in
microbial and algal biomasses are destroyed at these high
temperatures. Therefore, in order to preserve the value of the
residual biomass, the oil extraction should be carried out at mild
temperature conditions. Unfortunately, the oil resulting from
solvent extraction in mild process temperatures of, for example,
20.degree. C.-150.degree. C. usually results in a product rich in
metals and phosphorus impurity content. These type of oils can also
be very difficult to handle and purify by traditional means such as
degumming because of the presence of emulsifying compounds, such as
high level of phospholipids. Merely, the typical high original
amount of phospholipid in algal oil results in decreasing the oil
yield when using degumming resulting in ineconomical
processing.
[0008] US2009/0266743 discloses a method for thermally treating
triglyceride or triglyceride/hydrocarbon mixture for decreasing the
metal and phosphorus content. In this method hydrocarbon which has
a boiling point from about 25.degree. C. to about 760.degree. C.
including a large variety of hydrocarbon compounds and mixtures and
a triglyceride are passed through a heating zone. The temperature
in this zone is from about 40.degree. C. to about 540.degree. C. A
feed is produced which is contacted with a hydrotreating catalyst
in a reaction zone to produce a reaction product containing diesel
boiling range hydrocarbons.
[0009] WO2008034109 discloses a method for recovering fatty acids
in form of alkyl esters from microbial biomass, such as microalgae,
bacteria and fungi. The wet biomass is treated at high temperatures
up to 450.degree. C. and elevated pressure, such as up to 40 MPa
(about 400 bar). This high temperature treatment aims at and
results in disruption of the cells and formation of an oily phase.
An alcohol, such as methanol or ethanol, is added to the oily phase
and reacted therewith forming alkyl esters (FAME or FAEE).
Co-solvents, such as alkanes, and catalyst, such as organic acids,
can be used. Esterification reactions require essentially water
free environment and high amount of alcohol present.
[0010] Degumming is the process of removal of phospholipids,
including gums, typically from vegetable crude oil or edible oil
wherein they are dissolved. Especially hydratable phospholipids may
be removed by treatment with hot water. Oil containing
non-hydratable phospholipids require use of an acid, such as
phosphoric acid. Vegetable oils wherefrom hydratable phosphatides
have been eliminated by a aqueous degumming process, may be freed
from non-hydratable phosphatides by for example enzymatic
treatment.
[0011] Total hydrolysis of lipids to obtain free fatty acids is
well known and can be performed, for example, by treatment with
water i.e. hydrotreatment. Acylglycerols and phospholipids have
been successfully split or decomposed by hot pressurized water into
free fatty acid. Water simultaneously splits phospholipids and
glycerides to phosphate, glycerol and free fatty acids. However,
free fatty acids are known to be corrosive and causing problems in
subsequent processing. Therefore, extensive formation of free fatty
acids should be avoided.
[0012] EP2097496 discloses a process for direct conversion of
lipidic biomass to a transportation fuel. In this process lipidic
biomass comprising glycerides or materials resulting in
triglycerides is thermally hydrolysed with liquid water at about
220-300.degree. C. Glycerides and other oily components are totally
decomposed into free fatty acids and glycerol. The obtained free
fatty acids are processed further into jet fuel, gasoline or diesel
and glycerol is used as a combustable heat source in the treatment
process.
[0013] Prior art provides means for treating oily biomass by
conversion into esters or splitting into free fatty acid. However,
it would be preferred to obtain as high glyceride content for the
recovered oil as possible because of the corroding nature of free
fatty acids.
[0014] On the other hand, problematic phospholipids and other
complex lipids can be completely removed by degumming, which
however significantly lowers the yield. In degumming the complete
complex lipid is removed intact i.e. without decomposition or
structural decay thus lowering the yield of lipidic material
suitable for feedstock in further fuel production. For example,
phospholipids typically contain two long chain fatty acids which
are attached to the glycerol back bone and are suitable for
feedstock in fuel production. There remains a need for recovery of
the lipid components as intact as possible from the phospholipids
to enhance the overall quality of the recovered usable oil
fraction.
SUMMARY OF THE INVENTION
[0015] The object of the present invention is to provide a method
for efficient removal of impurities such as metals and phosphorus
from lipids originating from biological materials, especially
without lowering the yield of glyceridic material.
[0016] Another object of the present invention is to provide a
method for efficient removal of impurities such as metals and
phosphorus from biological materials comprising high amounts
thereof.
[0017] Yet, another object of the present invention is to maximize
the quality and amount of purified lipids to be obtained.
[0018] And yet, another object of the present invention is to
provide a method for producing lipids suitable for use in catalytic
refining processes for the production of various hydrocarbon
components, biofuel and renewable diesel.
[0019] Phospholipids typically tend to accumulate into the oil
phase together with the neutral lipids especially when extracting
vegetable or microbial biomass containing high amount of the
phospholipids.
[0020] According to an aspect of the present invention a mild heat
treatment to lipid material together with a suitable amount of
polar solvent such as water and nonpolar solvent such as heptane is
effective in the removal of phosphorus and metal impurities for
producing purified oils.
[0021] Hydrolysis of lipids is mainly a function of temperature, pH
and time. It was surprisingly found that when the lipids are
diluted in nonpolar solvent before subjecting them to elevated
temperature essentially no hydrolysis of the nonpolar lipids occur.
However, the vicinity of the water-solvent surface layer and thus
the presence of water increased the degree of phospholipid
hydrolysis. Therefore, in the method of the present invention the
nonpolar lipid tails are not essentially decomposed into free fatty
acids but merely remain in glyceride form. Thus, selective
hydrolysis of phospholipids resulting in a glyceride product with a
low level of phosphorus and metals is obtained. The phosphorus is
recovered as a solid metal phosphate and these beneficial nutrients
may be recycled back to e.g. algal cultivation.
[0022] Nutrient, especially phosphorus, recycling is a major
concern in the proposed algal to biofuel process and the present
invention provides an effective way to remove the phosphorus from
the oil without a loss of the valuable lipid tails.
[0023] In the method of the present invention a need for pre or
post processing for removal of phospholipids before the refining
steps is avoided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 shows the lipid quality in the original rapeseed oil
before treatment and the oil treated at 230.degree. C. with varying
oil/heptane ratio.
DETAILED DESCRIPTION OF THE INVENTION
[0025] The present invention relates to a method for treatment of
renewable lipid material, more specifically to a method for
purification of lipid material, wherein the oil or lipid comprised
in said lipid material originates from biological material. The
purified oil obtained by the method is suitable for use in fuel
production.
[0026] By the term "glyceride" is meant esters formed from glycerol
and fatty acids also known as acylglycerols.
[0027] By the term "renewable" is meant oil which originates from a
source other than crude oil i.e. from biological material such as
plant, animal and/or microbiological material.
[0028] More specifically, the present invention aims at removal of
phosphorus and metal impurities from lipid material in a way that
acylglycerols thereof stay essentially intact and there is very
little yield loss in the recovered oil fraction. The chemical
composition of the acylglycerols is in essence maintained i.e. for
example triacylglycerols (TAGs) are not converted into free fatty
acids. Virtually, none or only a small portion of the acylglycerols
present is chemically modified.
[0029] By "complex lipid" is meant lipid material containing a
further element in addition to C, H and O and/or having a
carbohydrate attached to the lipid. Typically, these elements
comprise phosphorus and nitrogen. Complex lipids are, for example
but not limited to, phospholipids, sphingolipids and
glycolipids.
[0030] By "biological material" is meant renewable organic material
containing oil, fats and/or lipids in general, which may be used
for oil recovery. This expression excludes oily components of
mineral oil in all its form or origin.
[0031] By the term "lipid" is meant a fatty substance, the molecule
of which generally contains at least partly an aliphatic
hydrocarbon chain, which dissolves in nonpolar organic solvents but
is poorly soluble in water. Lipids are an essential group of large
molecules in living cells. Lipids comprise, for example, fats,
oils, waxes, wax esters, sterols, terpenoids, isoprenoids,
carotenoids, polyhydroxyalkanoates, fatty acids, fatty alcohols,
fatty acid esters, phospholipids, glycolipids, sphingolipids and
acylglycerols, such as monoglycerols (monoacylglycerol, MAG),
diglycerols (diacylglycerol, DAG) or triglycerols (triacylglycerol,
TAG). The term lipid material further means material that comprises
an oil component which may be separated and recovered.
[0032] In the embodiments of the present invention lipids to be
treated include fats, oils, waxes and fatty acids and their
derivatives which are convertible into liquid form at the
processing conditions used.
[0033] The treatment method according to embodiments of the present
invention comprises at least the following steps:
[0034] a. Providing lipid material comprising acylglycerols and
phosphorus impurities and at least one added liquid nonpolar
solvent and at least one added liquid polar solvent into a reaction
zone whereby at least a two phase system is formed. Thus two phase
system comprises a nonpolar phase and a polar phase.
[0035] b. Heating said phase system in the closed reaction zone
under mixing at a temperature from 150.degree. C. to 300.degree. C.
The impurity content is still undesirably high if temperature is
lower than 150.degree. C. and if the temperature is risen above
300.degree. C., for example, acylglycerols tend to decompose.
Preferably, the treatment temperature is from 160.degree. C. to
260.degree. C. wherein a reasonable metal and phosphorus impurity
content for fuel component applications is reached and no essential
decomposition of acylglycerols takes place. The treatment is
perfomed at a pressure wherein said solvents are in subcritical
state, preferably of below 100 bar dependent on the vapor pressure
of the selected solvents, until the phosphorus impurity is removed
from the nonpolar phase.
[0036] c. Separating and recovering from said phase system said
nonpolar phase including the purified oil comprising
acylglycerols.
[0037] In embodiments of the present invention lipid material to be
treated preferably originates from biological material such as from
plants, animals or microorganisms.
[0038] According to a preferred embodiment the biological plant
material is a vegetable oil plant. Preferably, the lipid material
originating from these vegetable oil plants are seed oils,
vegetable oils, fruit oils or pine oils. More preferably, plant
material is selected from rapeseed, canola, soybean, palm, cotton,
sunflower, corn, camelina, jatropha, hemp and used cooking oil.
Vegetable oils generally contain quite low levels of phospholipids,
less than 5 wt %, and lower metal impurities than e.g. algal
oil.
[0039] According to another preferred embodiment the material
originating from animals comprises animal fat, preferably rendered
animal fat. Rendering can refer to any processing of animal
byproducts into more useful materials, or at least to the rendering
of whole animal fatty tissue into purified fats. A rendering
process typically yields a fat commodity such as yellow grease,
white grease, bleachable tallow or the like. Animal fat in
embodiments of the present invention is preferably selected from
beef, pork, sheep, and/or poultry lard, tallow, butter and/or
fat.
[0040] According to yet another preferred embodiment the biological
material is obtained from microorganisms. Preferred microorganisms
are algae, such as microalgae, bacteria, fungi, including
filamentous fungi and yeasts; more preferably algae and fungi, most
preferably algae. Especially algae oil purification is challenging
compared to e.g. rape seed oil purification due to high original
impurity content but yet successfully carried out by the method
according to embodiments of the present invention.
[0041] Most preferred algae are microalgae capable of incorporating
high lipid content such as microalgae genera comprising Achnantes,
Amphiprora, Amphora, Ankistrodesmus, Attheya, Boeklovia,
Botryococcus, Biddulphia, Brachiomonas, Bracteococcus, Carteria,
Chaetoceros, Characium, Chlamydomonas, Crypthecodinium,
Cryptomonas, Chiorella, Chlorococcum, Chrysophaera, Coccochioris,
Cocconeis, Cyclotella, Cylindrotheca, Dunaliella, Ellipsoidon,
Entomoneis, Euglena, Eremosphaera, Extubocellulus, Franceia,
Fragilaria, Gleothamnion, Hantzschia, Haematococcus, Hormotilopsis,
Hymenomonas, lsochrysis, Lepocinclis, Melosira, Minidiscus,
Micractinum, Monallanthus, Monoraphidium, Muriellopsis,
Nannochloris, Nannochloropsis, Navicula, Neochloris, Nephroselmis,
Nitzschia Ochromonas, Oedogonium, Oocystis, Papiliocellulus,
Parachlorella, Pascheria, Pavlova, Peridinium, Phaeodactylum,
Plankthothrix, Platymonas, Pleurochrysis, Pleurosigma,
Porphyridium, Prymnesium, Pseudochlorella, Pyramimonas, Pyrobotrus,
Radiosphaera, Rhodomonas, Rhodosorus, Sarcinoid, Scenedesmus,
Schizochytrium, Scrippsiella, Seminavis, Skeletonema, Spirogyra,
Stichococcus, Synedra, Tetraedron, Tetraselmis, Thalassiosira,
Trachyneis, Traustrochytrium, Trentepholia, Ulkenia, Viridiella,
and Volvox.
[0042] Preferred microorganisms further comprise cyanobacteria and
especially cyanobacteria selected from the group of Agmenellum,
Anabaena, Anabaenopsis, Arthrospira, Dermocarpa, Gleocapsa,
Microcystis, Nodularia, Nostoc, Oscillatoria, Plectonema,
Phormidium, Spirulina Synechococcus, Synechocystis and
Xenococcus.
[0043] Preferred fungal species are genera Aspergillus,
Mortierella, Chaetomium, Claviceps, Cladosporidium, Cunninghamella,
Emericella, Fusarium, Glomus, Mucor, Paecilomyces, Penicillium,
Pythium, Rhizopus, Trichoderma, Zygorhynchus, Humicola,
Cladosporium, Malbranchea, Ustilago. Preferred bacteria are those
belonging to the genera Acinetobacter, Actinobacter, Alcanivorax,
Aerogenes, Anabaena, Arthrobacter, Bacillus, Clostridium, Dietzia,
Gordonia, Escherichia, bacterium, Micrococcus, Mycobacterium,
Nocardia, Nostoc, Oscillatoria, Pseudomonas, Rhodococcus,
Rhodomicrobium, Rhodopseudomonas, Shewanella, Shigella,
Streptomyces and Vibrio.
[0044] Preferred oleaginous yeast are those belonging to genera
Clavispora, Deparyomyces, Pachysolen, Kluyveromyces, Galactomyces,
Hansenula, Saccharomyces, Waltomyces, Endomycopsis, Cryptococcus,
such as Cryptococcus curvatus, Rhodosporidium, such as
Rohodosporidium toruloides, Rhodotorula, such as Rhodotorula
glutinis, Yarrowia, such as Yarrowia lipolytica, Pichia, such as
Pichia stipitis, Candida such as Candida curvata, Lipomyces such as
Lipomyces starkeyi and Trichosporon such as Trichosporon cutaneum
or Trichosporon pullulans which readily accumulate lipids or have
been genetically modified to produce lipids.
[0045] There are at least two types of lipid material which are
preferably used in the present method. One is impure oil typically
directly originating from biomass and requires purification before
further processing. Main contaminants are metal impurities and
phospholipids. The other type is oil containing residue or waste
i.e. an oily residue or waste from a purification process such as
extraction wherein the material that still contains oil but cannot
be directly recycled and needs to be removed from the process. This
waste material typically originates from oil extraction or
purification processes and contains high amounts of impurities such
as phosphorus and metals but also lipid material in the form of
acylglycerols that can be used as feedstock in fuel production. The
present method is capable of recovering pure lipid material from
the oily waste material and increasing the yield. Preferably, the
oily waste material originates from a degumming process.
[0046] Depending on the feed the treatment comprises recovery of
oil from oily residue or purification of oil from impurities
residing therein.
[0047] In the first method step of embodiments of the present
invention lipid containing feed material is provided into a
reaction zone. Characteristic for this lipid feed material is that
it comprises acylglycerols and phosphorus impurities. In addition
to these components the lipid material preferably contains other
glycerides, more preferably triacylglycerols (TAGs),
diacylglycerols (DAGs), monoacylglycerols (MAGs) and possibly some
free fatty acids. The amount of glycerides and free fatty acids is
dependent on the origin of the oil.
[0048] The lipid material to be treated may also be solid or
semisolid such as fats. In order to perform an efficient treatment
the oil to be purified should be readily dissolvable in the
nonpolar solvent at the processing temperature and pressure. The
purified oil is recovered dissolved in the nonpolar solvent.
Impurities are removed from the nonpolar phase together with the
polar phase or as solid.
[0049] In a preferred embodiment the phosphorus impurities
originate from complex lipids.
[0050] The complex lipids contained in the lipid feed material
comprise preferably phospholipids. It may further comprise
sphingolipids and/or glycolipids. These lipids are the main source
for phosphorus, metal and/or nitrogen impurities in vegetable oils.
The amount of phospholipids is especially high when algal crude oil
is used as lipid feed.
[0051] In a preferred embodiment the lipid feed material contains
at least 1% by weight phospholipids.
[0052] In another embodiment the lipid feed material contains at
least 10% by weight phospholipids.
[0053] In a yet other embodiment the lipid feed material contains
at least 50% by weight phospholipids.
[0054] The amount of phospholipids in algae crude oil feed material
may be even up to 90% by weight of the oil therein.
[0055] The algae oil to be purified may further contain
carbohydrates, proteins, nucleic acids, solid residues, salts
chlorophylls, and other pigments. Moreover, said algae oil may
contain moisture originating, for example, from sea water which can
carry impurities.
[0056] According to one embodiment the lipid material to be treated
is purified before treatment by using water degumming in order to
recover the valuable lecithin.
[0057] Together with the lipid feed at least one liquid nonpolar
solvent and at least one liquid polar solvent are added into said
reaction zone together with the lipid feed material. Together all
these components form at least a two phase system including a polar
phase such as an aqueous phase and nonpolar oily phase.
[0058] In one embodiment when there is present an oily residue from
the degumming process a further phase emerges and a three phase
system is formed including a phase of solid gums, a polar phase and
a nonpolar phase.
[0059] In a preferred embodiment the lipid material is first
diluted by the nonpolar solvent and subsequently polar solvent is
added to this mixture. The nonpolar solvent readily dissolves the
neutral oil present in the lipid material and thus prevents
hydrolysis of it when adding the polar solvent.
[0060] Suitable nonpolar solvents for use in embodiments of the
present invention are nonpolar organic solvents. The nonpolar
solvent is preferably capable of dissolving the neutral oil
comprised in the lipid feed material and produced during the
treatment in hydrolysis of the more polar components, more
preferably dissolving the oil essentially completely. It is
furthermore preferred that said nonpolar solvent is more preferably
essentially totally immiscible with the polar solvent enabling
hydrolysis only at the interphase. The miscibility with a polar
phase results in yield loss and possible difficulties in phase
separation. Solvents fulfilling these criteria comprise aliphatic
or cyclic alkanes of C.sub.3-C.sub.20 or mixtures thereof.
Preferably C.sub.5-C.sub.16 alkanes or mixtures thereof are used
because of their suitable vapor pressure, which allows the solvent
to be separated from the lipid material more efficiently. Most
preferred alkanes comprise hexane, heptane or octane or mixtures
thereof. One favourable solution is to provide as a nonpolar
solvent an alkane product produced in the same manufacturing
facility, or otherwise readily available at the plant.
[0061] According to one preferred embodiment the nonpolar solvent
is a product from hydrodeoxygenation process, for example, a
product obtained from subsequent hydrodeoxygenation process after
purification of the oil whereby a recycle stream may be used.
[0062] According to one embodiment mixture of alkanes suitable for
oil refining and different gasoline distillation fractions may be
used. Preferably, these fractions contain hexane, heptanes, octane
or mixtures thereof. An example for a preferred suitable solvent is
refinery petroleum distillation fractions like low aromatic or
aromatic free hydrocarbon solvent mixtures such as NESSOL LIAV 110
(bp. 85-110.degree. C., available from Neste Oil), LIAV 230 (bp.
175-225.degree. C., available from Neste Oil) and the like. NESSOL
is a registered trade mark of Neste Oil Oyj, Finland.
[0063] In the method according to embodiments of the present
invention the ratio of said lipid material to said nonpolar solvent
is preferably less than 10:1 which is economically advantageous.
The ratio is more preferably less than 1:1 for efficiently
preserving the glyceridic oil, most preferably less than 1:5, most
preferably 1:10 in order to effectively prevent the
triacylglycerols or other neutral glyceridic oil from decomposing
and hydrolyzing.
[0064] The polar solvent to be added is preferably a solvent
capable of functioning as a carrier medium for the polar group of
said complex lipid. Without being bound by any theory, it has been
found advantageous for the process that there is a clear interphase
between the nonpolar and the polar phase, enabling more efficient
phase transitions of the impurities. For example, in case of
phospholipid as complex lipid the molecule contains a hydrophobic
tail i.e. long fatty acid hydrocarbon tail and a hydrophilic head
i.e. negatively charged phosphate group, and possibly other polar
groups. The uncharged hydrophobic tail is drawn to the nonpolar
solvent phase whereas the polar hydrophilic head of the molecule is
attracted by the polar solvent. Typically, when placed in water,
for example, phospholipids form a variety of structures depending
on the specific properties of the phospholipid.
[0065] In a preferred embodiment the polar solvent comprises water
or more preferably is water. This is the most economical choice.
However, a mixture of water and an alcohol readily soluble in water
is advantageous in some cases due to increased capacity of the
solvent to remove other than oil impurities, such as carbohydrates.
Most preferably, the alcohol is selected from methanol, ethanol and
a mixture thereof. Addition of organic acids which are considered
to effectively acidify the polar phase is advantageous in some
cases. Hydrolysis is enhanched in acid conditions but too acidic
conditions result in unwanted hydrolysis of the triglycerides. The
pH of the polar phase is preferably between 3 and 10.
[0066] In the method according to embodiments of the present
invention the ratio of the combined amount of said lipid material
to said polar solvent is preferably more than 1:10 in order to
ensure good contact with the nonpolar phase. The ratio is more
preferably more than 1:5 to enable effective mixing of the two
phases, most preferably equal to or more than 1:1, most preferably
5:4, or even such as 10:1. A low solvent ratio is advantageous to
avoid a large recirculation volume.
[0067] In the first step of the method according to embodiments of
the present invention all components are provided to the reaction
zone which resides in a closed environment such as a reactor able
to withstand the reaction conditions required.
[0068] In the seconds step the formed phase system is heated in
this closed reaction zone under mixing, preferably constant mixing.
The temperature needs to be carefully controlled and maintained at
about from 150.degree. C. to 300.degree. C., preferably from
160.degree. C. to 260.degree. C., to ensure that on the other hand
minimal degree of decomposition or pyrolysis takes place at the
higher end thus enabling the preservation of acylglycerols, such as
TAGs, intact and on the other hand effective removal of impurities
is obtained. The pressure building up in this closed system depends
on the treatment temperature chosen and the provided oil and
solvents. Typically, the pressure is such that the solvents are in
subcritical stage depending on the nature of the used solvents.
Preferably, the pressure is below 100 bar depending on the vapor
pressure of the selected solvents. Constant mixing is highly
advantageous to ensure good interfacial contact between the two
phases and materials dissolved therein. During constant mixing at
the chosen temperature and pressure the polar group of the complex
lipid is essentially detached from the uncharged portion.
[0069] The treatment temperature lower limit is preferably more
than 165.degree. C. due to enhanced purification and increased
separation of phospholipids. More preferably, the lower limit is
180.degree. C. due to increased separation of the metals such as
Ca.
[0070] Most preferably, the lower limit is at least 190.degree. C.
for improving the detachment of the charged group of the
phospholipid, such as 200.degree. C. To some extent the treatment
temperature is dependent on the origin of the oily material.
Purification of oil is a function of both the resident time and
temperature.
[0071] According to a preferred embodiment 30 min at 230.degree. C.
under mixing will remove more than 99,8% of phosphorus from
oil.
[0072] The upper limit of the treatment temperature is preferably
less than 300.degree. C. due to increased decomposition of TAG
taking place at higher temperatures. More preferably, the upper
limit is less than 265.degree. C., preferably less than 250.degree.
C., due to increased occurance of unwated side reactions at higher
temperatures. Most preferably, the upper limit is less than
240.degree. C. due to easier control of the pressure at lower
temperatures, such as less than 230.degree. C. To some extent the
treatment temperature is dependent on the origin of the lipid
material. Any combination of the treatment temperature ranges as
set above may be chosen depending on the effects to be pursued.
[0073] In a preferred embodiment the temperature in the second step
is from 210.degree. C. to 230.degree. C. for optimal
performance.
[0074] Furthermore, the selection of optimal temperature or
temperature range depends not only from the maximum yield of TAGs
or phosphorus purity possible to obtain but also on the further use
of the oil. For example, if the further use is in catalytic biofuel
refining process it sets criteria for the catalyst poison i.e.
metal and phosphorus content. It is not necessary to optimise the
process further after reaching low enough values. Moreover, the
quality of the recovered lipid, such as TAG content for example,
varies depending on the processing parameters used.
[0075] In a preferred embodiment the temperature in the second step
is from 200.degree. C. to 260.degree. C. with the provision that
said oil originates from algae.
[0076] In another preferred embodiment the temperature in the
second step is from 185.degree. C. to 230.degree. C. with the
provision said oil originates from vegetable plant fat.
[0077] Pressure during treatment is elevated due to increased
temperature as is typical in closed pressure vessels or reactors.
The treatment pressure depends on the selected temperature,
selected solvents i.e. the boiling points and vapour pressures
thereof and the reactor dead volume. A skilled person is able to
determine the pressure value based on theoretical calculation using
these parameters. In a batch operation mode typically about 65% is
effective volume whereas about 35% is dead volume. Preferably, the
solvents are chosen with the provision of at least 95%, preferably
98%, more preferably 99%, thereof being in liquid phase. A
preferred pressure range is from 2 to 100 bar, more preferably from
5 to 80 bar, most preferably from 10 to 70 bar, such as from 20 to
60 bar.
[0078] During the heat treatment step the mixing is preferably
efficient enough to provide an efficient mixing of the two phases
and for enabling good interfacial contact between the polar phase
and the nonpolar phase and materials dissolved therein. Efficient
mixing is preferably such that it enables the complex lipids to
migrate towards the polar solvent and enhances the removal of the
phosphorus. According to a preferred embodiment the mixing is
performed by using a mixing efficiency up to about 500 rpm for a
litre of water for 30 min, more preferably for 20 min.
[0079] Accoding to one embodiment of the present invention, in the
second step of the method the at least two phase system further
comprises solid impurities or solid phase residue is formed. During
mixing of the provided components or the heat treatment at elevated
pressure and constant mixing occationally a solid phase is formed.
The formation of the solid phase depends on the origin of the oily
material and the amount of impurities. Especially, when algae crude
oil is to be purified the oil frequently contains considerable
amounts of phospholipids resulting in high amounts of phosphorus
impurities and metal impurities. During separation of polar and
nonpolar components solid residue is often precipitated containing,
for example, sparingly soluble salts. For example, rapeseed
produces only modest residue due to low impurity content whereas
algae oil produces pronounced amount of residue due to high
impurity content. This solid phase residue may reside in the polar
phase or in the nonpolar phase, or possible both phases have some
residue therein. Thus, a distinct solid phase separates out from
said system forming said third phase. Especially when the treated
mixture is cooled down before removal from the reactor solid
precipitate emerge during cooling. Occationally, solid precipitate
forms already at the elevated temperature zone as some plugging of
filters can be observed after treatment.
[0080] Oil, such as rapeseed oil, originating from plant oils
containing relatively small amounts of phospholipids compared to,
for example, algae oils are also less difficult to purify. Mono and
divalent cations residing in or transported together with
phospholipids can be effectively removed by the treatment according
to embodiments of this invention compared to for example
traditional degumming methods. Metallic impurities tend to
accumulate in algal oils rendering the purication more challenging.
A marked decrease in metal content during purification is observed
using a method according to an embodiment of the present
invention.
[0081] After the heat treatment under elevated pressure and
constant mixing the formed nonpolar phase including the purified
oil is recovered in the third step of the present method. This
phase contains the purified oil dissolved in the nonpolar
solvent.
[0082] The nonpolar phase can be separated from the polar phase and
possible solid phase by generally known methods, such as settling,
decanting or centrifugation. If solids residue in the nonpolar or
polar phase they may be separated and collected by filtration or
centrifugation. Preferably, the solid phase residue is separated by
centrifugation.
[0083] In addition to previous steps the present method preferably
further comprises a step for separating said purified oil from said
nonpolar solvent of the nonpolar phase. More preferably, the
separation is carried out by evaporation.
[0084] According to a preferred embodiment the nonpolar solvent
used is recycled back to the first step after separation and
recovery of the purified oil component.
[0085] According to another preferred embodiment the polar solvent
used is recycled back to the first step after separation and
recovery thereof.
[0086] The most striking advantage of the present method is
observed in analysing the purified, separated and recovered oils.
Results show that excellent lipid quality is maintained during the
treatment. Only minor amount of TAGs or other glycerides such as
DAGs or MAGs have been hydrolysed or converted into free fatty
acids. Specifically, very low phosphorus content of oils
originating from algae suggest that successful recovery of neutral
lipids is possible from complex lipids otherwise totally removed in
traditional purification. The neutral portion of the complex lipids
is recovered in the nonpolar oil phase and increases the oil
yield.
[0087] In a preferred embodiment about 99%, preferably more than
99,5%, more preferably about 99,8%, of the phosphorus is removed
from algae oil originally containing about 6000 ppm phosphorus.
[0088] The lipid material to be treated may further comprise
nutrients such as nitrogen, potassium and/or phosphorus such as
nutrients originating from algae cultivation and carried during
harvesting and possible extraction into the algae crude oil. These
can generally be recovered from the polar phase after treatment
with this method.
[0089] According to a preferred embodiment the solid phase formed
is recycled to cultivation as a nutrient, for example, to algal
cultivation after separation and recovery thereof. Carbohydrates
and protein residues from the crude oil are typically dissolved in
the polar phase.
[0090] Using a method according to an embodiment of the present
invention the metal content of the purified lipids or the mixture
of lipids is lowered into about one twentieth or even one hundredth
part of the content in lipids originally. The obtained lipid
product contains clearly decreased amount of metals or metal salts.
Metallic impurities may comprise Al, Ca, Mg, Fe, Cr, Cu, Mo, Na,
Ni, Pb, Si, Sn, V, Zn, Mn which are detrimental for e.g. catalytic
oil refining. According to embodiments of the present invention the
total metal content is preferably decreased from several thousands
of ppms into reasonable ranges such as a few hundred ppms for
autotrophically cultured salt water algae, or less than 20 ppm,
preferably less than 10 ppm, more preferably even less than 5 ppm,
for heterotrophically grown species, vegetable or plant oil or
animal fat depending on the temperature and solvent combination
used.
[0091] In the present method the polar head containing phosphorous
and nitrogen of the phospholipids is selectively removed from the
lipid material or oil to be purified leaving the valuable fatty
acids components in the oil in the form of DAGs or MAGs, minimizing
the formation of free fatty acids. At the same time this separation
has shown minimal effect on the amounts of MAGs, DAGs and
especially TAGs residing in the nonpolar phase after treatment.
Without being bound to any theory it seems that methods according
to embodiments of the present invention is capable of selectively
hydrolyzing the phosphorous head of phospholipids, but not
hydrolyzing the fatty acids of TAGs, DAGs and MAGs, thereby
minimizing the formation of free fatty acids. The present method is
simultaneously capable of removing phosphorous by selective
hydrolysis, and metals from lipidic material.
[0092] The treatment of the present method may be performed in
industrial scale in continuous mode either counter currently or
concurrently by modifying the apparatus and process details which
is within the competence of a skilled person in the art.
[0093] In one embodiment the purified oil in the the nonpolar
solvent is used as a mixture for catalytic biofuel refining
processes.
[0094] A further advantage in the method according to embodiments
of the present invention is that any oil can be treated at elevated
temperature for removal of phosphorus and metal impurities.
Dilution by a nonpolar solvent effectively suppresses or prevents
the hydrolysis of lipids or oil.
[0095] A further aspect of embodiments of the present invention
provides the use of the purified oil obtained by the above
described method for production of biodiesel, renewable diesel, jet
fuel, gasoline or base oil components. Preferably, the method
according to an embodiments of the invention is used for purifying
oil originating from autotrophic algae. Moreover, the method
according to an embodiment the invention is preferably used for
purifying oil originating from rapeseed, heterotrophic organisms,
soybean or animal fat.
[0096] The invention and its embodiments are further illustrated by
examples but not restricted thereto.
EXAMPLES
[0097] The pressure reactor used for the experiments was from Parr
Instruments, model 4843. Heptane was n-heptane 99% pure (from J. T.
Baker), ethanol was denaturated and 99,5% pure (ETAX Ba,
Altia).
[0098] Gas Chromatograph (GC) used in analysis was a 6890N from
Agilent Technologies, and Ion Coupled Plasma (ICP) analyser was an
Optima 7300 DV from Perkin Elmer. Gel Permeation Cromatography
(GPC) was performed with a HPLC from Waters completed with three
GPC-columns (Agilent Plgel 500, 100, 50 .ANG., 5 .mu.m 7.8
mm.times.300 mm), a UV-detector (Waters 2996) and RI-detector
(Waters 2414). IR-analysis was performed with a Nicolet Avatar 360
FT-IR (Nicolet).
Example 1
[0099] Rapeseed oil (Raisio) was purified by diluting it with
heptane in a ratio of 1:3, and washing this oil-heptane solution
with equal amount of water by stirring these components in a
pressure reactor. In other words, a mixture of 40 g rapeseed oil,
120 g heptane, 160 g distilled water was mixed with a blade mixer
in a 1 liter pressure reactor using a mixing efficiency of 500 rpm
at varying temperatures for 30 min. Subsequently, the phases were
separated by centrifugation. The upper non-polar phase was
collected and the solvent heptane was evaporated therefrom in a
rotavapor to recover the purified oil component.
[0100] The total amount of free fatty acids in the oil was
determined by GC before and after the described treatment and after
lipid saponification and methylation required for the GC sample
preparation. The removal of phosphorus and metal impurities of the
oils were analyzed by ICP. The lipid profile was analysed by GPC.
The recovered and separated solids were analysed by IR after
drying.
[0101] The rapeseed oil was purified with the described wash
treatment at 190.degree. C., 200.degree. C., 210.degree. C.,
220.degree. C. and 230.degree. C.
[0102] The measured impurities of untreated and purified oils are
presented in Table 1.
[0103] The amount of impurities in the oil decreased notably in the
treatment. Heating at 230.degree. C. purified the oil to the extent
that the amount of all measured impurities were less than 1 ppm.
Only 11% of the triacylglycerols (TAGs) had undergone hydrolysis
and the purified oil contained only 4.5% free fatty acids (FFA). A
brown solid residue could be separated by centrifugation. The
residue contained phosphates and metals. The solid and water phase
were free of fatty acids based on IR-analysis after a wash with
heptane. In other words, all fatty acids were recovered in the
heptane phase.
[0104] This example indicates that rapeseed oil is effectively
purified with the thermal treatment using heptane and water with
only low hydrolysis of TAGs.
TABLE-US-00001 TABLE 1 Original rapeseed Oil treated Oil treated
Oil treated Oil treated Oil treated oil at 190.degree. C. at
200.degree. C. at 210.degree. C. at 220.degree. C. at 230.degree.
C. TAG wt-% 95.2 91.3 91.3 90.6 84.5 84.9 DAG wt-% 2.9 3.9 4.2 4.5
9.1 9.2 MAG wt-% <0.1 0.1 0.1 0.1 0.4 0.4 FFA wt-% 1.4 1.6 1.9
1.9 4 4.5 lipid wt-% 0.4 3.1 2.5 2.8 2 1.1 oligomers P mg/kg 264 17
2 1.3 1 <0.6 Ca mg/kg 209 22 0.8 0.6 0.9 <0.1 Mg mg/kg 49.6
1.3 <0.3 <0.3 <0.3 <0.3 Fe mg/kg 15 4.3 0.4 0.3 0.3
<0.1 Na mg/kg <0.5 <1.0 <1.0 <1.0 <1.0
<0.5
[0105] Values marked less than (<) a value means that the
impurity was below the detection limit.
Example 2
[0106] The treatment for rapeseed oil described in Example 1 was
performed at 230.degree. C. by varying the oil-heptane ratios. The
treatment was done at oil-heptane ratios 1:3, 1:1, and 3:1. The
oil-heptane mixture had a mass of 160 g. The water amount used was
equal to the nonpolar oil-heptane phase. On test was done with
oil-heptane ratio 1:3 but with 5 wt-% water. The results are
presented in Table 2 and. FIG. 1.
[0107] The result show that the oil diluted with the largest amount
of non-polar solvent was hydrolysed the least in the treatment.
When the treated oil was diluted in three parts heptane the
decrease in TAG content was only 11%. When the oil contained 25%
heptane, more than half of the TAGs (54%) were still unhydrolysed.
When decreasing the amount of water from 50 wt-% to 5 wt-% there
was slightly more TAGs unhydrolysed, however, only slightly more
phosphorus (1.1 ppm) was left in the oil.
[0108] This example indicates that the nonpolar solvent protects
the nonpolar oil from hydrolysis. The purification in view of
phosphorus and metals was similar in all treatments at 230.degree.
C. In other words, it is beneficial to dilute the oil in a nonpolar
solvent when hydrolysis of the oil is not desired and when
purifying oils rich in TAGs.
[0109] This example demonstrates that when a product high in TAGs
is required a purification treatment with the oil diluted in
nonpolar solvent is required to prevent major hydrolysis of the
lipids.
[0110] Table 2 shows the results for the rapeseed oil treated at
230.degree. C. with different dilutions in heptane.
TABLE-US-00002 TABLE 2 Original Oil/hept/water Oil/hept/water
Oil/hept/water Oil/hept/water rapeseed oil 1:3:4 1:1:2 3:1:4
1:3:0.2 TAG wt-% 95.2 84.9 64.9 53.9 87.8 DAG wt-% 2.9 9.2 19.9
24.5 7.4 MAG wt-% <0.1 0.4 2.2 3.8 0.2 FFA wt-% 1.4 4.5 11.4
16.3 3.2 lipid wt-% 0.4 1.1 1.6 1.6 1.5 oligomers P mg/kg 264
<0.6 1.1 0.9 1.1 Ca mg/kg 209 <0.1 0.3 <0.3 <0.3 Mg
mg/kg 49.6 <0.3 <0.3 <0.3 <0.3 Fe mg/kg 15 <0.1 1.1
0.8 0.4 Na mg/kg <0.5 <0.5 <1.0 <1.0 <1.0
[0111] FIG. 1 shows the lipid classes in the original rapeseed oil
and the oil treated at 230.degree. C. with different oil/heptane
ratio.
Example 3
[0112] Nannochloropsis oil, extracted from wet biomass at
100.degree. C. with heptane and ethanol (3:1), was treated by
diluting it with heptane in a ratio of 1:3, and treating this
oil-heptane solution with water-ethanol (1:3) solution of equal
mass in a stirred pressure reactor at set temperature. In other
words, a mixture of 40 g oil, 120 g heptane, 40 g ethanol and 120 g
distilled water was mixed in a 1 liter pressure reactor (mixing 500
rpm) at set temperature for 60 min. After this the phases were
separated by centrifugation. The upper non-polar phase was
collected and the solvent evaporated in a rotavapor to recover the
purified oil.
[0113] The total fatty acids of oil before and after treatment was
determined by GC after lipid saponification and methylation.
Impurities of the oils were analyzed with ICP-analysis. The lipid
profile was analysed by GPC-analysis. The separated solids were
analysed by IR after drying.
[0114] This oil was purified with the described treatment at
200.degree. C. and 225.degree. C.
[0115] The impurities of the original and purified oils are
presented in Table 3.
[0116] The level of phosphorus and metals decreased significantly
in treatments above 200.degree. C. In the wash at 200.degree. C.
the phosphorus content of the oil decreased by 65%, magnesium by
96%, sodium by 92% and calcium by 96%. In the wash at 225.degree.
C. the phosphorus content of the oil decreased by 99.5%, magnesium
by 99.9%, sodium by 99.5% and calcium by 99.9%.
[0117] This example indicates that oil is purified from phosphorus
and minerals by heating the oil to temperatures above 200.degree.
C., preferably over 225.degree. C. together with a polar solvent
such as water or water-EtOH mixture.
[0118] The solid separating in the treatment at 200-225.degree. C.
was analysed to contain metal phosphates and found valuable for
recycling back to the. cultivation.
[0119] Table 3 shows analysis results for original and treated
Nannochloropsis oil
TABLE-US-00003 TABLE 3 Original Oil treated Oil treated oil at
200.degree. C. at 225.degree. C. P mg/kg 6000 1550 31.4 Mg mg/kg
1620 49 1.1 Na mg/kg 1640 208 8 Ca mg/kg 1040 27 0.8
Example 4
[0120] The same Nannochloropsis oil as in Example 3 was treated at
230.degree. C. diluted in heptane (oil-heptane ratio 1:3). The
experiment was performed as in Example 3 with the difference that
the polar solvent (in Example 3 water and EtOH) was varied in the
different experiments to contain (1) water, (2) water-EtOH (3:1),
(3) water with acidic pH (2.6) and (4) water with basic pH (9.5).
Table 4 shows the analysis results for original and treated
Nannochloropsis oil.
[0121] The impurities were lowered very significantly in all
treatments. Very slight differences in level of impurities can be
seen decreasing the water amount, adding alcohol or adjusting the
pH of the water phase. Lowest phosphorus content (11.1 ppm) was
gained with acidic water. The phosphorus content of the oil was
thus lowered by 99.8%.
[0122] This example indicates that algal oil can be effectively
purified by heat treatment diluted in heptane and with a polar
solvent phase present during the treatment.
TABLE-US-00004 TABLE 4 Oil treated Oil treated Oil treated in Oil
treated in Oil treated in heptane in heptane heptane with heptane
with Original in heptane with 10.times. with water/ water of pH
water of pH oil with water less water EtOH (3:1) 2.6 9.5 P mg/kg
6000 16.9 16.9 19 11.1 14.9 Mg mg/kg 1620 1 1.7 3 <0.3 0.4 Na
mg/kg 1640 4.3 7.9 10 3.1 3 Ca mg/kg 1040 1.1 2.3 2.3 1.3 0.8
Example 5
[0123] Nannochioropsis oils extracted with hexane was treated at
230.degree. C. diluted in heptane (1:2) with added water
(oil-heptane-water ratio 1:2:1) like described in Example 1. The
results are shown in table 5.
[0124] The level of phosphorus was decresed significantly to 4 ppm.
Also the level of sodium, magnesium and calcium was effectively
reduced in the oil. This example indicates that the thermal
treatment with water is very effective for purification of algal
oil.
TABLE-US-00005 TABLE 5 Oil treated with Original heptane and water
at oil 230.degree. C. P mg/kg 584 4 Na mg/kg 483 1.1 Ca mg/kg 19.2
2.2 Mg mg/kg 219 0.7
Example 6
[0125] Dunaliella oil extracted from dry algal biomass with heptane
at 160.degree. C. was purified with the treatment as described in
Example 3 at 200.degree. C. and 220.degree. C. The impurities of
the original and purified oils are presented in table 6.
[0126] The impurities of the Dunaliella oil decreased notably. The
level of phosphorus decreased with 66%, magnesium, sodium and
calcium with over 95% in the treatment at 200.degree. C. At
220.degree. C. the phosphorus content decreased by 97%.
[0127] Algal oil of strain Dunaliella is significantly purified by
this thermal treatment. Best results are obtained at a temperature
of 220.degree. C. or higher.
TABLE-US-00006 TABLE 6 Original Oil treated Oil treated oil at
200.degree. C. at 220.degree. C. P mg/kg 178 61 4.9 Na mg/kg 308 2
1.2 Ca mg/kg 108 5 1.8 Mg mg/kg 136 <1 0.3
Example 7
[0128] Dry Rhodococcus bacterial biomass was extracted with heptane
at 100.degree. C. The extracted oil was, however, quite high in
phosphorus, sodium, magnesium and other minerals.
[0129] This oil was purified by diluting it with heptane in a ratio
of 1:3, and treating this oil heptane solution with water-ethanol
(1:3) solution at 200.degree. C. as described in Example 3.
[0130] The impurities in the original and the treated oil are
presented in table 7.
[0131] The impurities decreased significantly in the wash at
200.degree. C.; phosphorus decreased with 96%. Also magnesium (88%
decrease), sodium (98% decrease) and calcium (71% decrease)
decreased in the process. The lipid composition did not change
essentially from that of original extracted oil. Only minor
hydrolysis of the oil was detected at 200.degree. C.
[0132] This example indicates that bacterial oil with high
phosphorus and metal impurities is purified significantly by
treating the oil diluted in non-polar solvent with a polar water
containing solvent at elevated temperature of 200.degree. C. or
higher.
TABLE-US-00007 TABLE 7 Original Oil treated oil at 200.degree. C.
TAG wt-% 80.4 76.6 DAG. wt-% 5 7.4 MAG wt-% 0.8 0.8 FFA wt-% 3.2
4.5 lipid oligomers wt-% 10.6 10.6 P mg/kg 569 21 Mg mg/kg 122 15
Na mg/kg 651 16 Ca mg/kg 21 6
Example 8
[0133] Animal fat (Griffin Industries Inc.) was diluted with
heptane (oil-heptane ratio 1:3) and with water as the polar solvent
at 200.degree. C. and 240.degree. C. The treatment was performed as
described in Example 1.
[0134] The impurities in the original and treated oils are
presented in table 8.
[0135] The treatment with added water at 200.degree. C. and
240.degree. C. reduced the impurity content in the animal fat
product significantly. Phosphorus was reduced to 6.3 ppm at
200.degree. C. and was under the detection limit at 240.degree. C.
The animal fat treated at 240.degree. C. had the major part (62%)
of the TAGs unhydrolysed.
[0136] This example indicates that animal fat can be thermally
treated together with water to reduce phosphorus and metal contents
in the fat product significantly.
TABLE-US-00008 TABLE 8 Animal fat Animal fat treated with treated
with Original heptane and heptane and animal water at water at fat
200.degree. C. 240.degree. C. TAG wt-% 81.3 70 53 DAG wt-% 9.1 16
23.7 MAG wt-% 0.6 1.1 2.8 FFA wt-% 7 11.1 18.7 lipid wt-% 2 1.8 1.8
oligomers P mg/kg 95 6.3 <0.6 Na mg/kg 50 1 4.1 Ca mg/kg 30 3.9
8.8 Fe mg/kg 23 7 1.2 Mg mg/kg 5 0.2 0.4
Example 9
[0137] Soybean oil (Control Union Argentina) was diluted with
heptane (oil-heptane ratio 1:3) and treated with water as the polar
solvent at 240.degree. C. The treatment was performed as described
in Example 1.
[0138] The impurities in the original and treated oils are
presented in table 9.
[0139] The oil treated with added water was highly purified and
contained less than 0.6 ppm of any measured metal impurities.
[0140] This example indicates the added purity to soybean oil was
obtained when treating the oil with heptane and water at high
temperature with minor hydrolysis of the TAGs.
TABLE-US-00009 TABLE 9 Original Oil treated at oil 240.degree. C.
TAG wt-% 98 88.6 DAG wt-% 1 7.7 MAG wt-% 0.2 0.2 FFA wt-% 0.8 4.8
lipid oligomers wt-% <0.1 0.5 P mg/kg 87 <0.5 Mg mg/kg 12
<0.6 Ca mg/kg 20.3 <0.3 Na mg/kg <0.5 <0.5
Example 10
[0141] The treatment for rapeseed oil described in Example 1 was
performed at 230.degree. C. with the hydrodeoxygenation (HDO)
product of palm oil (hydrocarbon mixture) instead of heptane as
nonpolar solvent. The treatment was done at oil-HDO-product ratio
1:3. The oil-HDO-product mixture had a mass of 160 g. The water
amount used was equal to the nonpolar oil-HDO-product phase. The
water phase and solids were separated as described in example 1,
but the oil was not separated from the nonpolar solvent. The
analysis results for the purified oil-HDO-product are presented in
table 10.
[0142] The oil-HDO-product mixture obtained was highly purified and
contained less than 0.6 ppm of any measured metal impurities. This
example indicates that oil can be treated diluted in
hydrodeoxygenation product and yield a highly purified oil product
suitable for catalytic conversion processes.
TABLE-US-00010 TABLE 10 Untreated rapeseed Treated rapeseed
oil/HDO-product (1:3) oil/HDO-product (1:3) FFA wt-% 0.35 0.75 P
mg/kg 66 <0.6 Ca mg/kg 52 <0.3 Mg mg/kg 12 <0.3 Fe mg/kg 4
0.2
Example 11
[0143] Commercial lecithin (granular lecithin, Acros Organics),
which was analysed to contain 84% phospholipids, 14% neutral lipids
(mono-, di-, triglycerides and free fatty acids) and 2%
unidentified compounds, was diluted in heptane (16 g lecithin, 144
g heptane) and heated to 200.degree. C. and 240.degree. C. together
with water (160 g) like described in Example 1.
[0144] The oil-heptane phase was separated on top of the water
phase, filtered and heptane evaporated. The analysis results for
the obtained oils are presented in Table 11.
[0145] At 200.degree. C. 61% of the original lecithin was obtained
as oil. At 240.degree. C. 66% of lecithin was collected as oil.
According to these results lecithin phospholipids are partly
hydrolysed to di-, monoglycerides and free fatty acids, and the
phosphate is partly converted to solid precipitate and water
soluble phosphoric acid which was removed. All fatty acids from the
original lecithin were recovered in the oil-heptane phase according
to IR-analysis.
[0146] This example indicates that phospholipids can be thermally
broken down and oil essentially free of phosphorus and minerals can
be obtained from a material very high in phospholipids.
TABLE-US-00011 TABLE 11 Oil from Oil from treatment of treatment of
Original lecithin at lecithin at lecithin 200.degree. C.
240.degree. C. phospholipids wt-% 84 6 0.5 TAG wt-% 1.4 2.9 2.1 DAG
wt-% 8.8 37.2 36.6 MAG wt-% 3.2 17.3 21.2 FFA wt-% 0.3 36.6 38.5
lipid oligomers wt-% 0.3 0 0.6 P mg/kg 32700 2240 40.5 Mg mg/kg
2500 28 1.4 Ca mg/kg 1500 312 2.2 Fe mg/kg 16 9.3 2.4
Example 12
[0147] Rapeseed oil gums obtained from acid degumming of rape seed
oil (Raisio) was treated at 240.degree. C. with added heptane. The
gums contained mostly water (ca. 60%) and some residual
triacylglycerols (ca. 20%) from the separation of the hydrated
phospholipids (ca. 20%).
[0148] 226 g of the wet gums was heated together with 200 g heptane
at 240.degree. C. for 30 min under 500 rpm mixing in a Parr-reactor
as described in Example 1.
[0149] The analysis results of the obtained oil can be seen in
Table 12. Very pure oil in terms of phosphorus and metal content
can be obtained by this treatment. The oil obtained in the
treatment with heptane contains a significant amount of TAGs (43%)
which is lost to the gums during degumming. The hydrated
phospholipids are decomposed to DAG, MAG and FFA.
[0150] A brown solid residue could be separated by centrifugation.
The solid residue was analysed by IR to be mainly inorganic
phosphates. The separated water phase was brown and contained
dissolved material from the decomposed phospholipids, however, no
fatty acids were identified.
[0151] This example indicates that gums, waste from the degumming
of vegetable oils, can be heat treated as described and a very pure
oil can be obtained without any loss of fatty acids.
TABLE-US-00012 TABLE 12 Oil from treatment of wet gums with heptane
at 240.degree. C. TAG wt-% 43.1 DAG wt-% 25.8 MAG wt-% 8.9 FFA wt-%
21.9 lipid oligomers wt-% 0.3 P mg/kg 3.4 Mg mg/kg 0.2 Ca mg/kg 0.7
Na mg/kg 4.1 Fe mg/kg 0.9
Comparative Example 1
[0152] Different oils were treated at high temperature diluted in
nonpolar solvent without a polar solvent. Results are presented in
table 13.
[0153] Same rapeseed oil as in Example 1 was treated at 230.degree.
C. diluted in heptane (1:3) without water. After the treatment the
oil contained still 11 ppm phosphorus and some magnesium and
calcium which were removed in the treatments with water in Example
1.
[0154] Same Nannochloropsis oil as in Example 4 was treated at
230.degree. C. diluted in heptane (1:3) without adding water. A
significantly poorer result was seen when the polar phase was left
out entirely. The oil treated without water had 116 ppm phosphorus
and 78 ppm sodium remaining in the oil as compared to the results
gained (Example 4) when a polar phase was present (P less than 20
ppm, Na less than 10 ppm).
[0155] Same soybean oil as in Example 9 was treated at 240.degree.
C. diluted in haptane (1:3) without added water. The oil had after
the treatment still 16 ppm phosphorus left which would require an
additional purification step. In comparison the oil from the
treatment with water (Example 8) had very low impurities (under the
detection limit, less than 0.5 ppm).
[0156] This example demonstrates that significantly more impurities
(phosphorus and metals) are left in the oil after thermal treatment
if the polar phase is left out entirely.
TABLE-US-00013 TABLE 13 Comparison to example Comparison to example
Comparison to 1: Rapeseed oil treated 4: Nannochloropsis oil
example 9: Soybean diluted in heptane (1:3) diluted in heptane oil
diluted in heptane at 230.degree. C. (1:3) at 230.degree. C. (1:3)
at 240.degree. C. P mg/kg 11.1 116 16 Mg mg/kg 1.6 1 1.6 Na mg/kg
<0.5 1 0.5 Ca mg/kg 6.9 78 3.3
Comparative Example 2
[0157] The thermal treatment was performed for different oils
without dilution in nonpolar solvent. The results are presented in
table 14.
[0158] Same rapeseed oil as in example 2 was treated as such
(without heptane dilution) with water at 230.degree. C. A large
decrease in TAGs was seen after the treatment with water (oil-water
ratio 1:1). 65% of the TAGs were hydrolysed. When comparing this to
the results in Example 2 it is clearly beneficial to have heptane
diluting the oil in order to preserve the TAGs.
[0159] Same animal fat as in example 8 was also treated at
240.degree. C. with water (without heptane dilution) for
comparison. The treatment without heptane dilution at 240.degree.
C. resulted in a fat product highly hydrolysed (64.2% free fatty
acids, only 7% TAG). When comparing this result to the result in
Example 8 for the oil treated at the same conditions but together
with heptane, there was much less hydrolysis of the lipids (18.7%
FFA and 53% TAGs).
[0160] This example demonstrates that when treating the oil to be
purified without nonpolar solvent there is a clear increase in
hydrolysis of the oil. It is therefore clearly beneficial to treat
the oils diluted in e.g. heptane to keep TAGs as unhydrolysed as
possible.
TABLE-US-00014 TABLE 14 Comparison to Comparison to Example 2:
Rape- Example 8: Animal seed oil treated with fat treated with
water water (1:1) at 230.degree. C. (1:1) at 240.degree. C. TAG
wt-% 33.7 7 DAG wt-% 29 18.9 MAG wt-% 8.6 9.6 FFA wt-% 28.4 64.2
oligomers wt-% 0.3 0.2 P mg/kg <0.6 3.2 Ca mg/kg 3.8 14 Mg mg/kg
<0.3 2.1 Na mg/kg <1 6.2
Comparative Example 3
[0161] Same Nannochioropsis oil as in Example 5 was as a comparison
purified by traditional oil purification treatments degumming and
wet bleaching.
[0162] The degumming was performed by adding 2500 ppm of citric
acid and 2500 ppm of distilled water to the oil under high sheer
mixing with an Ultra-Turrax at 8000 rpm for 2 min at 50.degree. C.,
followed by 15 min mixing at 250 rpm with a magnetic stirrer. 750
ppm NaOH and 3 wt-% water was added to the oil after this. The
mixture was mixed at 8000 rpm (Ultra-Turrax) for 2 min and at 250
rpm (magnetic stirrer) for 60 min. Finally the mixture was
centrifuged at 50.degree. C. for 30 min and the degummed oil was
collected on top.
[0163] The degummed oil was after this wet bleached by adding 1000
ppm citric acid and 3000 ppm water followed by 8000 rpm mixing for
2 min and 250 rpm mixing for 15 min. 3 wt-% of bleaching clay was
added. The mixture was stirred for 30 min at 80.degree. C. The
mixture was then centrifuged for 10 min at 80.degree. C. and the
bleached oil was filtered and analysed.
[0164] The results are shown in Table 15.
[0165] The oil treated by thermal treatment at 230.degree. C. in
Example 5 contained only 4 ppm phosphorus and low amounts of
magnesium (0.7 ppm) and sodium (2.2 ppm). As a comparison the
degummed algal oil contained still half of the phosphorus in the
original oil as well as 319 ppm sodium and 72 ppm magnesium. Oil
further treated by wet bleaching contained a bit lower amount of
phosphorus (175 ppm), sodium (133 ppm) and magnesium (63 ppm),
however, considerably more than the thermally treated oil.
[0166] This example indicates that the thermal treatment was
significantly more effective in removing phosphorus and metal
impurities from algal oil than traditional degumming and bleaching
procedures routinely used for purification of vegetable oils.
TABLE-US-00015 TABLE 15 Original Oil treated Oil treated by algal
by acid acid dumming oil degumming and wet bleaching P mg/kg 584
262 175 Ca mg/kg 19.2 7.9 3.5 Na mg/kg 483 319 133 Mg mg/kg 219
71.8 62.9
Comparative Example 4
[0167] The treatment was performed as a comparison at lower
temperatures for certain oils.
[0168] The same Nannochioropsis oil as in Example 3 was treated at
the same dilutions but at room temperature and 100.degree. C.
[0169] The same Rhodococcus bacterial oil as in Example 7 was
treated at the same dilutions but at room temperature and
100.degree. C. The results are shown in Table 16.
[0170] This comparative example indicates clearly that wash
treatments at lower temperature did not enhance the purification of
the oils very significantly.
TABLE-US-00016 TABLE 16 Nanno- Nanno- Rhodo- Rhodo- chloropsis
chloropsis coccus coccus oil treated oil treated oil treated oil
treated at RT at 100.degree. C. at RT at 100.degree. C. P mg/kg
4800 4800 107 122 Mg mg/kg 1400 1370 63 53 Na mg/kg 1300 910 117
104 Ca mg/kg 867 864 16 15
* * * * *